First anti-symmetric (Ai) mode Lamb wave propagating in a LiTaO₃ thin plate at an Euler angle around (0°, 45°, 0°) has a high velocity. Both phase velocity and electromechanical coupling factor have been evaluated at different propagation angles (0°, 45°, ψ°). A1 mode Lamb wave at (0°, 45°, 0°) offers the highest velocity and largest electromechanical coupling factor, thus proving suitable for high frequency devices. Leaky Lamb waves' velocities have been measured for A0 and zero-th symmetric (S0) modes at different propagation angles by ultrasonic microscopy and are almost similar to the calculated Lamb wave velocities. Whereas Ai mode Lamb wave response has been evaluated at (0°, 42°, 0°), (0°, 42°, 45°) and (0°, 42°, 90°) using a network analyzer. The influence of Al-interdigital transducers' (IDT) thickness on the reflection coefficient has been evaluated for thin (0°, 39°, 0°) LiTaO₃. An IDT's thickness larger than 0.03λ (λ is the wavelength) is needed to fabricate A1 mode Lamb wave resonators.